Preparation Method and Application of Porous Poly(lactic acid) Membranes: A Review.

Porous membrane technology has garnered significant attention in the fields of separation and biology due to its remarkable contributions to green chemistry and sustainable development. The porous membranes fabricated from polylactic acid (PLA) possess numerous advantages, including a low relative density, a high specific surface area, biodegradability, and excellent biocompatibility. As a result, they exhibit promising prospects for various applications, such as oil-water separation, tissue engineering, and drug release. This paper provides an overview of recent research advancements in the fabrication of PLA membranes using electrospinning, the breath-figure method, and the phase separation method. Firstly, the principles of each method are elucidated from the perspective of pore formation. The correlation between the relevant parameters and pore structure is discussed and summarized, subsequently followed by a comparative analysis of the advantages and limitations of each method. Subsequently, this article presents the diverse applications of porous PLA membranes in tissue engineering, oil-water separation, and other fields. The current challenges faced by these membranes, however, encompass inadequate mechanical strength, limited production efficiency, and the complexity of pore structure control. Suggestions for enhancement, as well as future prospects, are provided accordingly.

The Structural Evolution of ß-to-α Phase Transition in the Annealing Process of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

In this study, the structural and property changes induced in the highly ordered structure of preoriented poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV films containing the ß-form during annealing were investigated. The transformation of the ß-form was investigated by means of in situ wide-angle X-ray diffraction (WAXD) using synchrotron X-rays. The comparison of PHBV films with the ß-form before and after annealing was performed using small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The evolution mechanism of ß-crystal transformation was elucidated. It was revealed that most of the highly oriented ß-form directly transforms into the highly oriented α-form, and there might be two kinds of transformations: (1) The ß-crystalline bundles may be transformed one by one rather than one part by one part during annealing before a certain annealing time. (2) The ß-crystalline bundles crack or the molecular chains of the ß-form are separated from the lateral side after annealing after a certain annealing time. A model to describe the microstructural evolution of the ordered structure during annealing was established based on the results obtained.

Comparative metabolism of two major compounds in Fructus Corni extracts by gut microflora from normal and chronic nephropathy rats in vitro by UPLC-Q-TOF/MS.

Herbal medicines are widely used as therapeutic products in many countries. Fructus Corni, a traditional herb medicine, has been clinically used to cure chronic nephropathy for thousands of years. It could be converted by gut microflora in vivo to shape its pharmacological profiles. Thus, metabolic profiles of major active constituents in Fructus Corni extracts by gut microflora from rats in healthy and nephropathy state were firstly investigated in vitro by ultraperformance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) in this study. According to the features of protonated ions, five metabolites (M1, M2, M3, M5 and M6) were found and preliminarily authenticated. Intestinal bacteria were capable of converting N0 (loganin) to its aglycone M1 (loganetin). The latter was further hydrogenated to the corresponding M2 (hydrogenated loganetin) and subsequently to M3 (hydrogenated and demethylated loganetin) by demethylation; While M5 (demethylated morronisid aglycone) and M6 (dehydroxylated morronisid aglycone) were identified as the two metabolites of N4 (morronisid) through demethylation and dehydroxylation. Gut microflora from healthy and nephropathy rats could degrade loganin and morronisid to the above metabolites. However, healthy rat intestinal bacteria showed more powerful degradation and much more amounts of M1 and M6 were obtained in their samples. Additionally, this work demonstrated that UPLC-Q-TOF/MS approach connected with MetaboLynx™ analysis software was rapid and reliable for screening and authentication of natural product metabolites.

[Effect of endophytic fungal elicitors on growth and atractylodin accumulation of cell suspension cultures of Atractylodes lancea].

OBJECTIVE: To investigate the effects of endophytic fungal elicitors on the growth and atractylodin accumulation of cell suspension cultures of Atractylodes lancea. METHOD: The endophytic fungal elicitors were added to the medium with different concentrations and culture period. Their effects on biomass, atractylodin content and relevant enzyme activities in suspension cultured cells were studied. RESULT: The cell growth was not affected by elicitors at low concentration and obviously inhibited at high concentration. Inhibition rate reached 46.7% by 100 mg L(-1) elicitor. In addition, six strains from A. lancea, among which Rhizoctonia SP1 activity was higher, had distinctly promoted the accumulation of atractylodin. Atractylodin biosynthesis was notably promoted by 20-60 mg L(-1) Rhizoctonia SP1 elicitor. When 40 mg L(-1) Rhizoctonia SP1 elicitor was added in the medium at the 12 day, the maximum content of atractylodin was 28.06 microg L(-1) at the 21 day with 48.3% higher than that of the control and PPO, POD and CAT activities remarkably increased. CONCLUSION: Adding the endophytic elicitors to the medium is able to be effective approaches to enhance atractylodin yield in the suspension culture cell of A. lancea.

Analysis of a Prophage Gene Frequency Revealed Population Variation of 'Candidatus Liberibacter asiaticus' from Two Citrus-Growing Provinces in China.

Prophages are important genetic elements of bacterial genomes and are involved in lateral gene transfer, pathogenicity, environmental adaptations, and interstrain genetic variability. In this study, the sequence of a prophage terminase gene of 'Candidatus Liberibacter asiaticus', a bacterium associated with citrus Huanglongbing (HLB), was selected as a molecular marker to assess the genetic variation in two 'Ca. L. asiaticus' populations from geographically distinct provinces (Guangdong and Yunnan) in China. The frequency of the prophage terminase gene was 15.8% (19/120) in Guangdong (altitude <500 m) and 97.4% (38/39) in Yunnan (altitude >2,000 m). The difference was highly significant (P < 0.0001) based on χ2 analysis. However, the partial prophage terminase gene sequences obtained from 10 Guangdong strains and 6 Yunnan strains were identical or highly similar, suggesting that at least some bacterial strains in the two locations shared a common recent origin. This is the first report on population variation of 'Ca. L. asiaticus' in China, where HLB was first described. The population variation of 'Ca. L. asiaticus' in the two geographical regions and the related HLB epidemiology were discussed.